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Study Provides Insights Into Autism and Epilepsy

August 31, 2009

Using funds from an Autism Speaks' grant, a team of researchers from Harvard University have uncovered the function of a gene known as LGI1, which was recently discovered to be linked to epilepsy. A mutation in LGI1 is the first genetic discovery that is clearly linked to partial epilepsy. Approximately 20% of individuals with an autism spectrum disorder (ASD) also have

epilepsy, with partial epilepsy being the most common form. Additionally, individuals with epilepsy who have the LGl1 mutation display language loss and impairment, resembling aspects of ASD. In the new studies, reported in the journal Nature Medicine, Matthew Anderson, M.D., Ph.D., and colleagues were able to show that the function of the LGl1 gene is to control the maturation of nerve cell signaling that occurs during the critical period of brain growth following birth. Although it's been known for a long time that nerve cells change the way they signal to each other in early postnatal life, the molecular processes that lead to this change in signaling have been unknown.

As the brain grows after birth, the underlying neuronal circuitry begins to change and mature. One particularly important feature during this critical maturation period is the sculpting of nerve cell connections, called synapses, that contain the excitatory neurotransmitter called glutamate. Anderson and his team found that when a mutation in LGl1 gene is present, synapses that use glutamate fail to mature to their final form. It is very possible that a similar process may contribute to partial epilepsy in autism.

These findings will provide a new avenue for scientists to gain an understanding of how nerve cell synapses develop and how that process may go awry. "By knowing the gene involved, we were able to model the mutation in mice, and this allowed us to find the biological impact of the mutation," explained Dr. Anderson. "Discovery that LGI1 mediates the process of excitatory synapse maturation during childhood brain development could provide insights into the cellular defects that underlie ASD, including epilepsy. Knowing the problem is the first step in being able to fix it."